Question
Consider the circuit in Figure 21.56, and suppose that the emfs are unknown and the currents are given to be I1=5.00 AI_1 = 5.00 \textrm{ A} , I2=3.0 AI_2 = 3.0 \textrm{ A} , and I3=−2.00 AI_3 = -2.00 \textrm{ A}. (a) Could you find the emfs? (b) What is wrong with the assumptions?
<b>Figure 21.56</b> A circuit with EMF's and resistors.
Figure 21.56 A circuit with EMF's and resistors.
Question by OpenStax is licensed under CC BY 4.0
Final Answer
  1. No, since I1≠I2+I3I_1 \neq I_2 + I_3
  2. Since the junction rule is violated, this circuit can not be solved with the information given.

Solution video

OpenStax College Physics for AP® Courses, Chapter 21, Problem 41 (Problems & Exercises)

OpenStax College Physics, Chapter 21, Problem 41 (PE) video thumbnail

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Video Transcript
This is College Physics Answers with Shaun Dychko. These values for the currents given to us for this circuit are not possible because if you apply the junction rule at point A, the currents going into it have to equal the total currents coming out. But the current I one being five amps does not equal three plus negative two. So since the junction rule is violated the circuit can't be solved with these numbers given.